Chemistry > AlkEnes > Flashcards

AlkEnes Flashcards

(46 cards)

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1
Q

What is the general formula for alkenes?

A

C_nH_(2n)

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2
Q

What is the functional group of alkenes?

A

C=C bond

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3
Q

what is name for c triple bond

A

alkynes

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4
Q

Why are alkenes very reactive?

A

The pi bond in the C=C bond has a low bond enthalpy

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5
Q

Define stereoisomers

A

Compounds with the same structural formula, but with a different arrangement in space

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6
Q

When can E/Z isomerism occur in alkenes?

A

When each carbon involved in the C=C bond has two different groups bonded to it

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7
Q

Pi bonds in e/z isomers

A

pi bond restricts rotation around c=c therefore each group are fixed relative to each other

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8
Q

When would an alkene not have stereoisomers?

A

If one or both the carbons involved in the C=C bond has two of the same groups attached

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9
Q

In stereoisomerism, how do you decide on priority groups?

A

Group with highest atomic number

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10
Q

How to explain if an alkene is an E isomer?

A

Priority groups are on opposite sides

e= enemies - opposite

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11
Q

How to explain if an alkene is a Z isomer?

A

Priority groups are on the same side

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12
Q

When can E/Z-isomers be referred to as cis or trans isomers?

A

must have one identical group of both c atoms in the c=c bond

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13
Q

trans

A

opposite

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14
Q

cis

A

same

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15
Q

Define electrophile

A

An electron pair acceptor

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16
Q

What type of reaction is alkene to alkane?

A

Electrophilic addition

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17
Q

What are the conditions and reagents for alkene to alkane?

A

Hydrogen; Nickel Catalyst

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18
Q

How are alkenes tested for?

A

Add bromine water; will be decolourised

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19
Q

What is the mechanism for bromine + ethene?

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A

Electrophilic addition mechanism

20
Q

What are the reagents and conditions to turn alkene to alcohol?

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A

Phosphoric acid catalyst; Steam

21
Q

What is the most stable carbocation?

22
Q

What is the least stable carbocation?

23
Q

In alkene reactions with hydrogen halides, to which carbocation will the hydrogen go?

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A

The least stable

24
Q

In alkene reactions with hydrogen halides, to which carbocation will the nucleophile (halogen) go?

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A

The most stable carbocation

25
draw and label a pi bond
26
Displayed formula equation for ethene to ethane
27
Type of reaction for alkene to halogenalkane
electrophilic addition
28
Displayed formula equation for Alkene to alcohol
29
primary carbocation
30
Secondary carbocation
31
Tertiary carbocation
32
draw the mechanism for an alkene reaction with hydrogen halide, including both major and minor products
33
Explain the three ways in which addition polymers can be destoryed
1- Combustion - releases lots of energy for electricity--> fuel for energy 2- Feedstock recycling 3- Recycling
34
issues with disposal of polymers
1- lack reactivity 2- non - biodegradable
35
Displayed formula equation for addition polymerisation of ethene
36
Why is combustion of addition polymers an issue
Results in formation of HCl and CO Which are toxic
37
How can HCl be removed as a product from combusting addition polymers
Passing it through an alkali
38
Why are biodegradeable and photodegradable polymers more beneficial to the enviroment
As they don’t need to be incinerates So there is no formation of HCl and CO Which are toxic
39
What is the functional group of the alcohol homologous series
-OH (hydroxyl)
40
reagents and conditions for alkene to haloalkane
halogenation -room temp and halogen halide or gaseous hydrogen halide room temp addition reactions
41
conditions for polymerisation
heat (high temp) and pressure and use of catalyst
42
1- the priority group around the double bond are on opposite sides 2- higher priority groups are c6h5 and cho 3- lower priority groups are H and CH3
43
alkenes are more chemically reactive than the alkanes
c=c contain higher e- density than c-c pi bonds weaker than sigma more likely to be attacked by an electrophile
44
major products key words
formed from secondary carbocation which is more stable than primary
45
unsaturation test
1- bromine water --> shows presence of c=c bond 2- decolourised orange to colourless
46
state and explain the features of hex2-ene molecule that lead to E and Z isomers (2)
contains c=c bond which has restricted rotation due to pi bonds groups are fixed relative to each other each carbon atom in c=c bond has two different groups attached
Chemistry
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